Speaker

ABSTRACT

A speaker having a drive cone and a diaphragm which can deal with higher output. The speaker comprises a frame, a magnetic circuit section, and a vibrating section. The magnetic circuit section is fixed to the frame. The vibrating section is housed in the frame and includes a drive cone ( 14 ) and a diaphragm ( 15 ) which are vibrated by the magnetic circuit section. The drive cone ( 14 ) has a coniacal cone body ( 47 ), outer steps ( 48 ) and inner steps ( 49 ). A plurality of outer steps ( 48 ) are provided at the outer edge of the cone body ( 47 ) while spaced apart along the circumferential direction. A plurality of inner steps ( 49 ) are provided at the inner edge of the cone body ( 47 ) while spaced apart along the circumferential direction. The steps ( 48, 49 ) are formed flatly along the vibrating direction of the drive cone ( 14 ), i.e. the direction intersecting the central axis perpendicularly. A gold thread ( 36 ) is secured to each of the steps ( 48, 49 ).

TECHNICAL FIELD

This invention relates to a speaker for generating sound by vibrating adrive cone with a speech current supplied.

BACKGROUND

Various speakers have been equipped in motor vehicles as disclosed in,for example Patent Document 1. The speaker described in the PatentDocument 1 includes a frame, a vibration portion, and a magneticcircuit. The vibration portion is received in the frame. The magneticcircuit is attached to the frame and generates sound by vibrating thevibration portion.

The vibration portion includes a voice coil for supplying speechcurrent, a voice coil bobbin of which the voice coil is coiled around anouter circumference, a drive cone attached to the voice coil bobbin, anda diaphragm attached to the drive cone. The exterior of drive cone isformed into a cone shape and sheet like shape. The magnetic circuitincludes a permanent magnet. The voice coil is arranged in the magneticgap.

In the speaker described above, when the speech current is supplied tothe voice coil, electromagnetic force (Lorentz force) affects in thevoice coil, and the diaphragm is vibrated through the drive cone.Thereby, the speaker generates sound responsive to the speech current.

[Patent Document 1] Japanese Application for utility model registrationNo. S63-158091

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

In the speaker described in the Patent Document 1, the drive cone isformed into a gently sloping cone shape so as to reduce the thickness ofthe speaker. In recent years, a speaker for playing sound at full blast(hereafter, high power output) is required in a speaker mounted in motorvehicles. In order to respond to the high power output, it is necessaryto form the drive cone into a sharply sloping cone shape.

However, when the speaker is played at full volume, amplitude of thedrive cone increases. Thereby, the drive cone requires more mechanicalstrength. As shown in the Patent Document 1 described above, when thedrive cone is formed into a thin plate shape, it is difficult tomaintain mechanical strength which is required for the high poweroutput.

It is an object of the present invention to provide a speaker having adrive cone or a diaphragm which can correspond to the high power outputmore.

Means for Solving Problem

According to a first aspect of the present invention, a speaker includesa frame, a magnetic circuit attached to the frame, and a vibrationportion. The vibration portion has a voice coil accepting a speechcurrent, a diaphragm and a drive cone. The drive cone is formed into acone shape, and transmits a vibration of the voice coil to thediaphragm. A step portion which is flat along a direction perpendicularto a vibration direction of the drive cone is provided on the drivecone.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] A sectional view showing an embodiment of a speaker accordingto the present invention.

[FIG. 2] A front view showing a condition removing a diaphragm of thespeaker or a center cap shown in FIG. 1.

[FIG. 3] A perspective view seeing the drive cone of the speaker shownin FIG. 1 from a back side.

[FIG. 4] A plan view seeing the drive cone shown in FIG. 3 from the backside.

[FIG. 5] A sectional view taken along section V-V of FIG. 4.

[FIG. 6] A sectional view showing a second embodiment of a speakeraccording to the present invention.

EXPLANATIONS OF LETTERS OR NUMERALS

-   1 speaker-   2 magnetic circuit-   3 vibrating part-   4 frame-   12 voice coil-   14 drive cone-   15 diaphragm-   36 tinsel wire-   48 outside step portion (step portion)-   49 inside step portion (step portion)-   50 through hole-   51 fixing pin (holding portion)-   52 through hole-   53 fixing hole (holding portion)-   58 through hole-   59 step portion-   60 damper-   K space

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, a first embodiment of the present invention is explained. Ina speaker of the embodiment of the present invention, a step portionwhich is flat in a direction perpendicular to a vibration direction isprovided on the drive cone. Thereby, the speaker of the presentinvention improves mechanical strength of the drive cone. For thisreason, the speaker can provide the drive cone with adequate mechanicalstrength against the high power output. Therefore, the speakercorresponding to the high power output can be provided.

Also, the speaker may fix a tinsel wire on the step portion. In thiscase, when the tinsel wire is fixed with glue in assembling, the gluefixes securely on the step portion. Thereby, the tinsel wire can beassuredly fixed on the drive cone.

Furthermore, the step portion fixing the tinsel wire may be arranged onboth an inner edge of the drive cone and an outer edge of the drivecone. In this case, the tinsel wire can be fixed on the inner edge andthe outer edge of drive cone. Thereby, even if the speaker is played atfull volume, the tinsel wire does not come away from the drive cone.That is, the tinsel wire can be prevented from falling off from thedrive cone.

It is preferable to arrange the step portion fixing the tinsel wire in acircumferential direction of the drive cone at intervals. In this case,when force is applied to the drive cone from the tinsel wire, weightbalance of the drive cone becomes equal. Thereby, vibration of the drivecone can be prevented from exerting a bad affect by the tinsel wire. Inaddition, by equalizing the weigh balance of the drive cone, weighbalance of the vibrating part can be equalized.

In the speaker of the present invention, air of a space sealed betweenthe drive cone and a diaphragm is generated, and is used as springcharacteristic of air spring. The spring characteristic as the airspring absorbs vibration energy of voice coil bobbin and the diaphragm,and reduces a vibration of their voice coil bobbin. For this reason, adamper arranged on a conventional speaker is not required. Therefore,construction of the speaker can be simplified.

Embodiment

A first embodiment of the present invention is explained by referring toFIGS. 1-5. A speaker 1 of the first embodiment shown in FIG. 1 isequipped in a vehicle such as a motor vehicle and provides soundinformation to a passenger.

As shown in FIG. 1, the speaker 1 includes a frame 4, a magnetic circuit2, a vibration portion 3 generating sound, and a wiring structure 5.

As shown in FIG. 1, the frame 4 includes a frame body 20, a connecterframe 21, a cover 22 for magnetic circuit, and a gasket 23.

The frame body 20 is made of metal such as aluminum. The frame body 20includes a bottom portion 24 of a ring shape, a cylindrical cylinder 25projecting from an outer edge of the bottom portion, and a flange 26projecting from an inner surface of the cylinder 25. In one end of thecylinder 25 on the bottom portion 24, an opening 27 passing through thecylinder 25 (that is, the frame body 20) is arranged. A plurality of theopenings 27 is arranged in a circumferential direction of the frame body20 at intervals

The flange 26 is formed into a ring shape, and projects from the innersurface of the cylinder 25 toward an inner side of the cylinder 25. Theflange 26 is arranged along the inner surface of the cylinder 25 and allaround an inner edge portion of the cylinder 25. In the flange 26, ahole 28 is arranged. A tube member 38 described below is pressed in thehole 28. The hole 28 passes through the frame body 20 of the frame 4.That is, the hole 28 passes through the flange 26.

The connecter frame 21 blocks the opening 27 of the frame body 20, andis attached to the frame body 20. A connector 29 is attached to theconnector frame 21. The connector 29 can connect to an amplifier mountedin a vehicle. The connector 29 may connect to another electric device.

The cover 22 for magnetic circuit includes an annular bottom portion 30,a tube 31 upstanding from an outer edge of the bottom portion 30. Thecover 22 for magnetic circuit is fixed on a yoke 7 of the magneticcircuit 2 by a bolt 32. Furthermore, a plate 9 and the frame body 20 arefixed by a bolt 33. When the cover 22 for magnetic circuit is fixed inthe frame body 20, the cover 22 and the frame body 20 are coaxiallyarranged. That is, central axes of the cover 22 and the frame body 20are same.

The gasket 23 is formed into a ring shape. The gasket is overlapped withan outer edge portion (an outer circumference portion) of the frame body20. The gasket 23 sandwiches an edge 18 with the outer edge portion, andis fixed in the frame body 20 with glue. Also, the gasket 23 sandwichesthe edge 18 between the outer edge portion of the frame body 20, andfixes a diaphragm 15 described below in the frame body 20.

The magnetic circuit 2 is fixed in both the cover 22 and the frame body20, and attached to the frame 4. As shown in FIG. 1, the magneticcircuit 2 includes the yoke 7, a magnet 8, and the plate 9. The yoke 7is formed from a magnetic material such as paramagnetic or ferromagneticmaterial. The plate 9 is formed from a magnetic material such asparamagnetic or ferromagnetic material. The yoke 7 includes an annularbottom plate 10 and a cylindrical center pole 11 upstanding from aninner edge of the bottom plate 10. In this embodiment, magnetic circuitof outer magnet type is disclosed. However, it is possible to apply thepresent invention to various magnetic circuits (for example, innermagnet type or combination of inner and outer magnet type, that is,magnetic circuit arranging magnet in an inside and outside of voice coilbobbin). Furthermore, an opening leading into an outside of a speakerdevice is formed in the center pole in the embodiment but not limitedthereto.

The magnet 8 is formed into a ring shape. An inner diameter of themagnet 8 is larger than an outer diameter of the center pole 11. Themagnet 8 is superposed on the bottom plate 10 and allows the cylindricalcenter pole 11 to pass therethrough. The magnet 8 may be excited with apermanent magnet or a direct current.

The plate 9 is formed into a ring shape. An inner diameter of the plate9 is larger than an outer diameter of the center pole 11. The plate 9 issuperposed on the magnet 8 and allows the center pole 11 of the yoke 7and a voice coil bobbin 13 to pass through the center portion thereof.The yoke 7, magnet 8, and plate 9 are coaxially disposed to each other.Inner surfaces of the magnet 8 and plate 9 have a space against an outersurface of the center pole 11 of the yoke 7.

The yoke 7 is fixed in the cover 22 for magnetic circuit by the bolt 32passing through the bottom portion 30 and the bottom plate 10. Also, theplate 9 is fixed on the frame body 20 by screwing the bolt 33 passingthrough the bottom portion 24 of the frame body 20 thereto. Therefore,since the plate 9 is fixed on the frame body 20 and the bottom plate 10is fixed in the cover 22 for magnetic circuit, the magnetic circuit 2 isfixed on the frame 4. The yoke 7, magnet 8, and plate 9 are coaxial withthe frame 4.

The magnetic circuit 2 has a magnetic gap G between the outer surface ofthe center pole 11 of the yoke 7 and the inner surface of the plate 9.The magnetic gap G has a large magnetic flux density. That is, themagnetic circuit 2 vibrates the drive cone 14, 15 by generatingelectromagnetic force (Lorentz force) with the voice coil 12 in themagnetic gap G.

The vibration portion 3 is received in the frame body 20 of the frame 4.The vibration portion 3 includes a voice coil 12, the voice coil bobbin13, a drive cone 14, the diaphragm 15 and a center cap 16. In theembodiment, two voice coils 12 are included, and two voice coil bobbins13 are winded together (not shown). The two voice coils 12 are coaxiallyarranged each other before the diaphragm 15 is driven, and placed in themagnetic gap G of the magnetic circuit 2. Speech current is supplied tothe two voice coils 12.

The voice coil bobbin 13 has a tube shape. An inner diameter of thevoice coil bobbin 13 is larger than the outer diameter of the centerpole 11 of the yoke 7. An outer diameter of the voice coil bobbin 13 issmaller than the inner diameter of the plate 9 and magnet 8. The voicecoil bobbin 13 is coaxial with the yoke 7, the plate 9 and voice coil12. One end portion of the voice coil bobbin 13 is inserted in themagnetic gap G, and attached with the voice coil 12 around an outersurface of the one end. The voice coil bobbin 13 is movably supportedwith the drive cone 14 and the diaphragm 15 along an axis of the yoke 7.The axis of the yoke 7 is also the axis of the speaker 1.

The drive cone 14 transmits vibration of the voice coil 12 to thediaphragm 15. The drive cone 14 is formed with a synthetic resin. Thedrive cone 14 is formed into a cone shape. An inner edge of the drivecone 14 is attached to an outer surface of the other end in a centralaxis direction of the voice coil bobbin 13. Thereby, the drive cone 14is attached to the voice coil 12 through the voice coil bobbin 13.

As shown in FIGS. 3 and 4, the drive cone 14 has integrally a cone body47, a plurality of outside step portions 48, and a plurality of insidestep portions 49. The cone body 47 is formed into a cone shape. Theoutside step portion 48 and the inside step portion 49 are a stepportion which is flat along a direction perpendicular to a vibrationdirection of the drive cone 14. The outside step portion 48 and theinside step portion 49 are provided with the same number of tinsel wires36 described below. That is, in FIG. 2, the four tinsel wires arearranged. The outside step portion 48 and the inside step portion 49respectively corresponds to the tinsel wire 36 one to one.

The outside step portion 48 and the inside step portion 49 are providedalong a vibration direction of the drive cone 14. That is, the outsidestep portion 48 and the inside step portion 49 are formed in a directionperpendicular to a central axis. The outside step portions 48 arearranged at intervals around the drive cone 14 of the speaker 1. Also,the inside step portions 49 are arranged at intervals around the drivecone 14 of the speaker 1. The outside step portion 48 is arranged on anouter edge of the cone body 47 of the drive cone 14. The plurality ofoutside step portions 48 are respectively arranged along thecircumferential direction of the cone body 47 of the drive cone 14.

The outside step portion 48 has a through hole 50 and a pair of fixingpins 51 as a holding portion. The through hole 50 is arranged in thecenter of the outside step portion 48. As shown in FIG. 5, the throughhole 50 passes through the center of the outside step portion 48, andgoes the tinsel wire 36 through an inside. The pair of fixing pins 51project from the outside step portion 48 toward the diaphragm 15. Thethrough hole 50 is arranged near the fixing pin 51. The tinsel wire 36passing through the through hole 50 is sandwiched between the fixingpins 51. Thereby, the pair of the fixing pins 51 fixes the tinsel wire36 in the outside step portion 48. That is, the tinsel wire 36 is fixedon the drive cone 14.

The inside step portion 49 is arranged on an inner edge of the cone body47 of the drive cone 14. The plurality of inside step portions 49 arerespectively arranged along the circumferential direction of the conebody 47 of the drive cone 14.

As shown in FIG. 4, a through hole 52 and fixing hole 53 as a holdingportion is arranged on the inside step portion 49. The through hole 52is arranged on one end near the outside step portion 48 corresponding tothe inside step portion 49. As shown in FIG. 5, the through hole 52passes through one end of the inside step portion 49, and threads thetinsel wire 36 through an inside. The fixing hole 53 passes through thecenter of the inside step portion 49, and is arranged in concurrencewith the through hole 52 along the circumferential direction.Furthermore, the fixing hole 53 passes through a terminal of the tinselwire 36 passed through the through hole 52, and fixes the tinsel wire 36in the inside step portion 49. That is, the tinsel wire 36 is fixed inthe drive cone 14.

In an outer edge of the drive cone 14, an edge 17 is attached with glue.The edge 17 is formed into an annular and flat shape, and deformable.Connection of the edge 17 and the drive cone 14 can use known means suchas a screwing or sewing method except the glue. The edge 17 issandwiched between the flange 26 of the frame body 20 and a positioningmember 34 of the wiring structure 5, and fixed by them. That is, thedrive cone 14 is attached to the frame body 20 in the frame 4 throughthe edge 17.

The diaphragm 15 is made of a synthetic resin, and formed into a ringshape. An inner diameter of the diaphragm 15 is larger than an innerdiameter of the drive cone 14, and an outer diameter of the diaphragm 15is larger than an outer diameter of the drive cone 14. The diaphragm 15is fixed in a part of the drive cone 14 and grooves 55, 56, 57 shown inFIG. 1 with glue. In an outer edge of the diaphragm 15, the edge 18 isattached with glue. A cross section shape of the edge 18 is formed intoa semicircle and sheet-like shape. The outer edge of the edge 18 issandwiched between the outer edge of the cylinder 25 of the frame body20 and the gasket 23, and fixed on the cylinder 25 and the gasket 23.That is, the diaphragm 15 is attached to the frame body 20 of the frame40 through the edge 18.

The center cap 16 is made of a synthetic resin, and formed into acircular shape. A central portion of a cross section shape of the centercap 16 projects toward an acoustic radiation direction. Also, thecentral portion is formed into a concave shape from the center portiontoward the outer edge. An outer diameter of the center cap 16 is largerthan the inner diameter of the drive cone 14 and is smaller than theouter diameter of the diaphragm 15. The outer edge of the center cap 16is superposed on the diaphragm 15, and attached to the diaphragm 15 withglue all around the outer edge.

The drive cone 14 of the vibration portion 3, the diaphragm 15 and thecenter cap 16 are coaxially disposed to the frame 4 and the magneticcircuit 2. When the current (speech current) depending on soundinformation is supplied to the voice coil 12, the vibration of the voicecoil 12 is transmitted to the diaphragm 15 by the drive cone 14. Andthen, the diaphragm 15 vibrates along the central axis, and thevibration portion 3 generates sound according to the speech current.

A space K surrounded with the drive cone 14, the diaphragm 15, the edges17, 18 and the inner surface of the frame body 20 of the frame 4 issealed. That is, the space K is kept with airtight condition.

Thereby, in the vibration portion 3, the voice coil bobbin 13 vibratesalong a central axis direction. When the drive cone 14 and the diaphragm15 vibrate, the drive cone 14, the diaphragm 15 and the edges 17, 18 aredisplaced. Thereby, air in the space K between the drive cone 14 and thediaphragm 15 repeats compression and expansion. As a result, springcharacteristic as an air spring is generated.

In the embodiment, when effective area of the diaphragm 15 is S1 andeffective area of the drive cone 14 is S2, difference S of effectivearea is S=S1−S2. Furthermore, when volume of air in the space K betweenthe drive cone 14 and the diaphragm 15 is V, stiffness constantexpressing the spring characteristic of air spring is proportional toS/V. That is, in the embodiment, the air of the space K sealed betweenthe drive cone 14 and the diaphragm 15 is generated. And then, the airis used as the spring characteristic as the air spring. Thereby,abnormal movement (for example, the diaphragm 15 operates with verylarge amplitude) can be controlled. Furthermore, acousticcharacteristics of the speaker 1 can be continuously reproduced, and beplayed over long periods. Also, reliability of the speaker 1 can bemaintained even if the diaphragm 15 vibrates over long periods withlarge amplitude.

As shown in FIG. 2, the wiring structure includes the positioning member34, a fuse 35, a plurality of tinsel wires 36, a plurality of lead wires37 and a tube member 38. The positioning member 34, as shown in FIG. 2,has a member body 39 and a press contact terminal 40. A part of thepress contact terminal 40 is molded into the member body 39. An outerdiameter of the member body 39 is formed into a ring shape, and isapproximately equal in size to the inner diameter of the cylinder 25 ofthe frame body 20. The member body 39 has a bottom plate 41, a pluralityof inner walls 42, and a plurality of positioning pins 43. The bottomplate 41 is superposed on the flange 26. The plurality of inner walls 42projects from an inner edge of the bottom plate 41, and have spacesalong the circumferential direction. The plurality of positioning pins43 projects from a center of radial direction of the bottom plate 41,and have spaces along the circumferential direction.

The bottom plate 41 of the positioning member 34 of the member body 39sandwiches an outer edge of the edge 17 with the flanges 26, and thepositioning member 34 of the member body 39 is fixed on the flange 26 ofthe frame body 20 with a bolt or glue not shown. Thereby, thepositioning member 34 of the member body 39 is arranged in the space K.The inner wall 42 and the positioning pin 43 sandwich the lead wire 37between each other, and determine a position of the lead wires 37 alongan inner surface of the cylinder 25 of the frame body 20 of the frame 4.That is, the positioning member 34 determines the position of the leadwires 37 along the inner surface of the cylinder 25 of the frame body 20in the frame 4. In the member body 39, as shown in FIG. 1, when themember body 39 is attached to the flange 26, a cutout portion 44overlapping with the hole 28 is provided.

The press contact terminal 40 is formed from a conductive metal plate,and has integrally a pair of pressure welding blades 45 upstanding fromthe member body 39 and a connection portion not shown. The connectionportion connects with the pair of pressure welding blades 45 and isburied in the member body 39. In the press contact blade 45 of the presscontact terminal 40, the tinsel wire 36 or the lead wire 37 is inserted.

In the FIG. 2, the six pressure welding terminals 40 are provided, andarranged at regular intervals in the circumferential direction of themember body 39. When the positioning member 34 is fixed in the frame 4,two of the six pressure welding terminals 40 are arranged near the hole28. The other four are arranged away from the hole 28.

In FIG. 2, the two fuses 35 are provided. As shown in FIG. 2, the fuse35 is inserted into the pressure welding blade 45 of the pressurewelding terminal 40 coming close to each other, which is one of theother four pressure welding terminals 40 arranged away from the hole 28.The pressure welding terminals 40 coming close to each other areconnected with the fuse 35. Therefore, the fuse 35 is arranged in thespace K. The fuse 35 is connected to the lead wire 37 and the tinselwire 36 in series. When the speech current supplied to the voice coil 12exceeds a predetermined current value, the fuse 35 blows out. Thereby,supply to voice coil 12 from the speech current is stopped.

In FIG. 2, the two tinsel wires 36 are provided. One end of the tinselwire 36 is passed through the through hole 50 provided on the outsidestep portion 48 from an inside of the frame body 20 of the drive cone14. Thereafter, the one end of the tinsel wire 36 is passed through thethrough hole 52 arranged on the inside step portion 49 and the fixinghole 53 in turn. And then, the tinsel wire 36 is connected to a topportion of the voice coil 12. In this time, the tinsel wire 36 issandwiched between the pair of the fixing pins 51 provided on theoutside step portion 48, and is fixed in the outside step portion 48.Glue including such as a silicon rubber is filled around the tinsel wire36, the through holes 50, 52 and the fixing hole 53. The spacetherebetween is sealed. The tinsel wire 36 is fixed on the drive cone 14with the glue.

Since the tinsel wire 36 is fixed in the outside step portion 48 and theinside step portion 49, the tinsel wire 36 have spaces along thecircumferential direction of the drive cone 14. Furthermore, the tinselwire 36 is pulled out from outer surfaces of the voice coil bobbin 13and the drive cone 14 toward the positioning member 34 (that is, spaceK) along the radial direction of the speaker 1.

Each of the two tinsel wires 36 is pressed into the press contact blade45 provided away from the hole 28 of the pressure of welding terminal40, which is one of the four pressure welding terminals 40 arranged awayfrom the hole 28. The other two tinsel wires 36 are pressed into thepress contact blade 45 provided away from the hole 28 of the presscontact terminal 40, which is one of the other two pressure weldingterminals 40 arranged near the hole 28, and connected to the presscontact terminal 40.

The lead wire 37 is a covered electric wire having a conductive core anda covering portion of insulation. In Figs, the four lead wires 37 areprovided. The two lead wires 37 are pressed into the press contact blade45 near the hole 28 of the pressure of welding terminal 40, which is oneof the four pressure welding terminals 40 arranged away from the hole28, and connected to the press contact terminal 40. The other two leadwires 37 are pressed into the press contact blade 45 near the hole 28 ofthe press contact terminal 40, which is one of the other two pressurewelding terminals 40 arranged near the hole 28, and connected to thepress contact terminal 40.

Thereby, the lead wire 37 is connected to the voice coil 12 through thepress contact terminal 40 and the tinsel wire 36. On condition that thelead wire 37 is sandwiched between the inner wall 42 and the positioningpin 43 and positioned, the lead wire 37 is wired from the press contactblade 45 toward the cutout portion 44 (that is, toward the hole 28). Thelead wire 37 supplies the speech current to the voice coil 12.

The tube member 38 is made of rubber, and formed into a cylindricalshape. The tube member 38 may be made of synthetic resin material. Thetube member 38 is molded by insert molding so that the rubber is coveredaround the four lead wires 37 respectively. The tube member 38 passesall of four lead wires 37 through inside, and the four lead wires 37 arebound. And then, the tube member 38 is pressed into the hole 28, andattached to the frame body 20 of the frame 4. The tube member 38 passesall of the four lead wires 37 through inside, and leads the four leadwires 37 to an outside of the space K. The lead wire 37 is attached to aterminal 46 of the connector 29 in the outside of the space K. When thedrive cone 14 and the diaphragm 15 vibrate, the tube member 38 keeps inair tight condition so as to prevent air of the space K from leaking outof the space K through the hole 28. In order to keep the space K in airtight, it is preferred that the tube member 38 is made of elasticrubber.

The wiring structure 5 presses the fuse 35, the tinsel wire 36, and thelead wire 37 into the desired press contact blade 45, and inserts thetube member 38 passing through all of the four lead wires 37 into thehole 28. Thereby, the lead wire 37 is attached to the terminal 46 of theconnector 29 and assembled.

The tinsel wire 36 is attached to the drive cone 14 as below oncondition that the outside step portion 48 and the inside step portion49 are parallel to a horizontal direction. The tinsel wire 36 issandwiched between the pair of the fixing pins 51 provided on theoutside step portion 48 of the drive cone 14 from the back of the framebody 20 beyond the drive cone 14, and is passed through the through hole50. And then, the tinsel wire 36 is passed through the through hole 52and the fixing hole 53 provided on the inside step portion 49 in turn.Thereafter, the tinsel wire 36 is fixed in the drive cone 14 by the gluefilled around the through holes 50, 52 and the fixing hole 53. In thistime, the glue seals spaces between the through holes 50, 52, the fixinghole 53 and the tinsel wire 36. The spaces between the through holes 50,52, the fixing hole 53 and the tinsel wire 36 are kept with airtightcondition.

The wiring structure 5 connects the lead wire 37, the fuse 35, thetinsel wire 36 and the voice coil 12 in series, and supplies the speechcurrent supplied to the terminal 46 of the connector 29 to the voicecoil 12.

In the above speaker 1, the speech current is supplied to the voice coil12 through the lead wire 37 of the wiring structure 5. According to thespeech current, the voice coil 12 arranged in the magnetic gap Gvibrates along the central axis. Furthermore, the voice coil bobbin 13around the outer circumference of which the voice coil 12 is coiledthereof vibrates along the central axis with the drive cone 14 and thediaphragm 15. That is, vibration of the voice coil 12 is transmitted tothe diaphragm 15 by the drive cone 14, and the diaphragm 15 vibrates. Byvibrating the diaphragm 15, sound depending on the speech current isgenerated. In this way, the magnetic circuit 2 vibrates the diaphragm 15(that is, the vibration portion 3) and generates sound.

In this embodiment, the step portion (that is, the outside step portion48 and the inside step portion 49) which is flat in a directionperpendicular to a vibration direction of the drive cone 14 is arrangedon the drive cone 14. Thereby, the mechanical strength of the drive cone14 is improved. Additionally, the adequate mechanical strength againstthe high power output can be given to the drive cone 14. Therefore, thespeaker 1 corresponding to the high power output can be provided.

The speaker 1 fixes the tinsel wire 36 in the outside step portion 48and the inside step portion 49. Thereby, when the tinsel wire 36 isfixed with the glue in assembling, the glue fixes securely on theoutside step portion 48 and the inside step portion 49 (that is, stepportions). Therefore, the tinsel wire 36 can be assuredly fixed on thedrive cone 14.

In addition, the outside step portion 48 and the inside step portion 49which fix the tinsel wire 36 are provided on both the inner edge and theouter edge of the drive cone 14. Thereby, the tinsel wire 36 can befixed in both the inner edge and the outer edge of the drive cone 14.Even if the speaker 1 is played at full volume, the tinsel wire 36 canbe prevented from falling off the drive cone 14. That is, even if thehigh power output of the speaker 1 is performed, the tinsel wire 36 doesnot fall from the drive cone 14.

In this embodiment, a step portion 59 which is flat in a vibrationdirection of the voice coil 12 (that is, a direction perpendicular tothe central axis) is arranged on the drive cone 14. Thereby, mechanicalstrength of the drive cone 14 is increased. That is, rigidity of drivecone 14 can increase by providing the step portion 59. As a result,adequate mechanical strength can be given to the drive cone 14 againstthe high power output. Therefore, the speaker 1 corresponding to thehigh power output can be provided. It is desirable to have a space in acircumferential direction of the drive cone 14 between the step portions(that is, the outside step portions 48 and the inside step portions 49)fixing the tinsel wire 36. In this case, when force acting on the drivecone 14 from the tinsel wire 36 is applied, weight balance of the drivecone 14 becomes equal. Thereby, vibration of the drive cone 14 can beprevented from negative effects of the tinsel wire 36. Furthermore,since weight balance of the drive cone 14 can be equalized, weightbalance of the vibration portion 3 can be equalized.

In the speaker 1, air of space sealed between the drive cone 14 and thediaphragm 15 is generated, and is used as spring characteristic of airspring. The spring characteristic as the air spring absorbs vibrationenergy of the voice coil bobbin 13 and the diaphragm 15, and reducesvibration of their voice coil bobbin 13. For this reason, a damperarranged on a conventional speaker is not required. That is to say, inthe speaker 1 of the embodiment, the drive cone 14 and the diaphragm 15combine a damper decreasing vibrations of the drive cone 14 and thevoice coil bobbin 13. Thereby, it is not necessary to equip the dampersupporting the voice coil bobbin 13 behind the drive cone 14 and thediaphragm 15. Also, axial size of the speaker 1 can be reduced byomitting the damper and installation space thereof. Additionally, it ispossible to produce a thin speaker required with an audio system mountedon a vehicle. Therefore, construction of the speaker 1 can besimplified.

The drive cone 14, which is concentrically equipped behind of thediaphragm 15 so as to maintain the sealed space K between the drive cone14 and the diaphragm 15, may be made of material in common with thediaphragm 15. Thereby, comparing the speaker 1 of the present inventionto the conventional speaker having a damper, mechanical fatigue isalmost not generated in the speaker 1. Therefore, decreased reliabilityof a speaker device being caused by mechanical fatigue of components canbe prevented, and the speaker 1 can be used for a long life.

Furthermore, in order to prevent lateral vibration (that is, movement ofa perpendicular direction against a central axis of voice coil) of thediaphragm of the voice coil, the voice coil bobbin, or the drive cone, adamper having accordion structure (corrugation damper) deforms in theperpendicular direction against the central axis. However, in the drivecone 14 and the diaphragm 15, a large deformation is not locally caused.For this reason, peculiar vibration such as a rolling phenomenon causinga bad sound quality or rubbing sound, which is produced by the contactof the voice coil bobbin 13 with the plate 9 or the magnet 8, is notgenerated. Therefore, the speaker 1 can be played with high qualitysound.

In the speaker 1, when the diaphragm 15 is vibrating, air of the sealedspace K between the drive cone 14 and the diaphragm 15 repeats cycle ofcompression and expansion. Thereby, in the edges 17, 18 of the drivecone 14 and the diaphragm 15 deformation by air pressure (back pressure)receiving with a back surface thereof is not caused. As a result, thedrive cone 14 and the diaphragm 15 can be vibrated with large amplitudewithout generation of the peculiar vibration or the rubbing sounddescribed above. In addition, sound can be played at full volume.Furthermore, by the air spring in which the air of the space K isgenerated, the drive cone 14 and the edge 17 can control abnormalmovement (for example, the diaphragm 15 operates with very largeamplitude). Acoustic characteristics of the speaker 1 can becontinuously reproduced, and be played over long periods. Also,reliability of the speaker 1 can be maintained even if the diaphragm 15vibrates over long periods with large amplitude.

In the above embodiment, the two voice coils 12, the four tinsel wires36, and the four lead wires 37 are provided. However, in the presentinvention, one or more than three voice coils 12 may be provided, andtwo or more than four tinsel wires 36 and lead wires 37 may be provided.Furthermore, as shown in the speaker 1 of second embodiment of thepresent invention shown in FIG. 6, the step portion 59 which is flat ina direction perpendicular to a vibration direction of the diaphragm 15may be provided on the diaphragm 15. In this second embodiment shown inFIG. 6, for some elements same with those of the first embodiment, samereference numerals are used, and explanations are omitted. The speaker 1shown in FIG. 6 includes the diaphragm 15 and a damper 60. The drivecone 14 is not included. In this second embodiment, one end of thedamper 60 is fixed in the voice coil bobbin 13, and the other end isfixed in the frame body 20 of the frame 4. The step portion 59 which isflat in a direction perpendicular to a vibration direction of thediaphragm 15 is provided on the diaphragm 15. A through hole 58 and aholding portion not shown are provided on the step portion 59. Thethrough hole 58 passes through the tinsel wire 36. The holding portionfixes the tinsel wire 36 on the step portion 59. The tinsel wire 36passing through the through hole 58 is fixed on the holding portion.Thereafter, the tinsel wire 36 is fixed in the step portion 59 (That is,the diaphragm 15) with glue. As with the above first embodiment, thestep portion 59 which is flat in a vibration direction (that is, adirection perpendicular to the central axis) is arranged on thediaphragm 15. Thereby, mechanical strength of the diaphragm 15 isincreased. More specifically, by providing the step portion 59, rigidityof the diaphragm 15 can increase. For this reason, adequate mechanicalstrength can be given to the diaphragm 15 against the high power output.Therefore, the speaker 1 corresponding to the high power output can beprovided.

The speaker 1 fixes the tinsel wire 36 in the step portion 59. Thereby,when the tinsel lead wire 36 is fixed with glue in assembling, the gluefixes securely on the step portion 59. Therefore, the tinsel wire 36 canbe assuredly fixed on the diaphragm 15.

According to the above embodiments, the following speaker 1 is provided.

(Additional statement) The speaker 1 includes the frame 4, the magneticcircuit 2 attached to the frame 4, and the vibration portion 3. Thevibration portion 3 has the voice coil 12 in which speech current issupplied, the diaphragm 15, and the drive cone 14. The drive cone 14 isformed into a cone shape, and transmits vibration of the voice coil 12to the diaphragm 14. In the speaker 1, the step portions 48, 49 whichare flat in a direction perpendicular to a vibration direction of thedrive cone 14 are arranged on the drive cone 14.

According to the additional statement, the step portions 48, 49 whichare flat in the vibration direction of the drive cone 14 (that is, in adirection perpendicular to the central axis) is arranged on the drivecone 14. Thereby, mechanical strength of the drive cone 14 is increased.For this reason, mechanical strength can be given to the drive cone 14against the high power output. Therefore, the speaker 1 corresponding tothe high power output can be provided.

The embodiment described above is only exemplary and the presentinvention is not limited thereto and includes any modification andalteration within the scope of the present invention.

1. A speaker comprising: a frame; a magnetic circuit attached to theframe; and a vibration portion having a voice coil accepting a speechcurrent, a diaphragm, and a cone-shaped drive cone transmittingvibration of the voice coil to the diaphragm; wherein a step portionwhich is a flat along a direction perpendicular to a vibration directionof the drive cone is provided on the drive cone.
 2. The speaker asclaimed in claim 1, wherein a holding portion fixing a tinsel wire forsupplying the speech current to the voice coil is provided on the stepportion.
 3. The speaker as claimed in claim 1, wherein a through hole isformed in the step portion, and the tinsel wire is passed through thethrough hole.
 4. The speaker as claimed in claim 1, wherein the stepportion is provided on both an outer edge of the drive cone and an inneredge thereof.
 5. The speaker as claimed in claim 1, wherein a pluralityof the step portions is spaced each other around the drive cone.
 6. Thespeaker as claimed in any one of claims 1 to 5, wherein space surroundedby the frame, the drive cone and the diaphragm is sealed.
 7. A speakercomprising: a frame; a magnetic circuit attached to the frame; and avibration portion having a voice coil accepting a speech current and adiaphragm; wherein a step portion which is flat along a directionperpendicular to a vibration direction of the diaphragm is provided onthe diaphragm.
 8. The speaker as claimed in claim 7, wherein a holdingportion fixing a tinsel wire for supplying the speech current to thevoice coil is provided on the step portion.
 9. The speaker as claimed inclaim 7, wherein a through hole is formed in the step portion, and thetinsel wire is passed through the through hole.